Houston Texans inside linebacker Brian Cushing (56) is congratulated by teammates after an interception in the first quarter of their NFL Wild Card Round game at NRG Stadium on January 9, 2016 in Houston. File photo by Erik Williams/UPI | License Photo

HOUSTON -- Surrounded by cameras inside the Houston Texans' locker room, a contrite Brian Cushing got choked up as the veteran linebacker discussed the 10-game suspension he served for violating the NFL performance-enhancing drug policy.

Although the former NFL Defensive Rookie of the Year was forthcoming about his emotions, he declined to specify what substance triggered his second violation of the league policy since entering the NFL.

Cushing did say the punishment stemmed from him failing to seek permission from the league office for a prescription medication.

Cushing added that the suspension, which he didn't appeal, didn't stem from taking Adderall. When questioned, he hinted that it was not a steroid or HGH substance.

"I don't want to get too much into particulars, but there were a good amount of things bothering me in this past offseason, most mentally, and I was getting a prescription medication that I should have been more careful with and should have communicated with the league a lot better about," Cushing said. "I take full responsibility for it and it's something now that I'm working with the league and taking again, through their terms and through their doctors to OK it.

"The encouraging thing is there are other guys in the league that are allowed to take this. That's the process we're in right now, to hopefully get that done."

Cushing served a four-game suspension in 2010, his second season with the team, after being a first-round draft choice from USC. It was reported at the time that Cushing tested positive as a rookie for a fertility drug called HCG, which is on the banned substance list and has frequently been used to restart natural testosterone production.

Cushing alluded to players dealing with CTE and other issues relating to head injuries as a motivation for him taking the medication without seeking approval from the NFL.

"I hope they understand that I had an issue that I was trying to better myself with," Cushing said. "As I've gotten older, there's been a lot of things that I've been worrisome about, especially with a lot of the other players that have played and retired and kind of the situations and conditions they're in."

Rumors about steroid use have dogged Cushing for his entire football career going back to his days playing high school ball in New Jersey and at USC. This suspension reinforced those perceptions surrounding Cushing with plenty of criticism and ridicule delivered to the former Pro Bowl selection via social media.

"There's a massive range of things that you can test positive for," Cushing said. "Extremely frustrating. I've been tested hundreds of times throughout my career. For it to happen again, I should have communicated with the league a lot better about it and been more careful.

"I understand that, but I continue to plan to play for a good amount more. I understand that's what comes with it, but I'll obviously try to build that back up and do it the right way."

Cushing was activated from a roster exemption this week, and Texans head coach Bill O'Brien said he expects him to play Sunday against the San Francisco 49ers.

"He and I have a good relationship," O'Brien said. "I have a lot of respect for him. He came back in, we talked for a while, I told him kind of what our plans were for him, especially relative to last week. We wanted to see what type of shape he was in. There's a difference between working out in a gym somewhere and being in football shape, so we wanted to have a week to do that.

"He's a Texan and it was great to have him back. I don't think anybody's on a pitch count this time of the year. We have to find a way to win. I think it all depends on how the game unfolds. He'll be in there, though."

Cushing expressed regret that he let his teammates and coaches down by not being available to play for the majority of the season.

"Just very regretful and I felt terrible about it, just a terrible situation," Cushing said. "Any time I'm absent from here I feel like I let a lot of guys down, let a lot of fans down. The worst part is just watching guys and knowing you can't help. This is everything I love doing, so, yeah, it hurt a lot."

Signed to a six-year, $52.5 million contract, Cushing is due non-guaranteed base salaries of $7.25 million next season and $8.25 million in 2019. Cushing could be cut without creating any dead money under the salary cap this offseason. The Texans are well stocked at inside linebacker with Benardrick McKinney, Zach Cunningham and Dylan Cole, which could make Cushing expendable.

"I would like to play football, but at the same time I can't worry about that," Cushing said. "That's a decision that's out of my hands. I can play the best football I possibly can and leave that decision up to them. What's done is done and I can't worry too much about the past. I just have to continue to move forward and like I said, play the best football I can for this team."

SERIES HISTORY: 4th regular-season meeting. 49ers lead series, 2-1. The Texans lost 34-3 to the 49ers on Oct. 6, 2013.